1. Field of the Invention
The present invention relates to a three-dimensional photonic crystal and a process for the production thereof as well as a probe used therefor, and more particularly to a three-dimensional photonic crystal into which an optical phase shift region (defect region) can be inserted arbitrarily, so that which is used suitably in case of constituting semi-conductor lasers, optical waveguides and the like, and a process for the production thereof as well as a probe used therefor.
2. Description of the Related Art
Heretofore, a photonic crystal having a similarity as that of solid crystal and involving an artificial periodic structure has been known. More specifically, photonic crystal is the one having a two- or a three-dimensionally periodic structure wherein two or more types of dielectrics, semiconductors, metals and air are alternately disposed in a repeated manner with a period corresponding to around optical wavelengths.
In the present specification, it is to be noted that photonic crystal having a two-dimensionally periodic structure is referred to as “two-dimensional photonic crystal”, while photonic crystal having a three-dimensionally periodic structure is referred to as “three-dimensional photonic crystal”.
In solid crystal, atoms are disposed periodically wherein a wave of electron exhibits a certain particular behavior while capturing a periodicity of the crystal. Likewise, in a periodic structure of photonic crystal, not a wave of electrons, but a wave of light exhibits a certain particular behavior, which is determined by energy dispersion characteristics and referred to as photonic band. Furthermore, in photonic crystal, it is possible to produce a forbidden gap wherein existence of light can be forbidden, which is referred to as “photonic bandgap”.
From the facts as described above, it is assumed that there is a high possibility being capable of freely controlling light by an optical device constituted from three-dimensional photonic crystals, as in the case where a semiconductor device can control freely electrons.
For this reason, a manner for producing three-dimensional photonic crystals has been proposed heretofore as a pre-requisite for fabricating an optical device constituted by three-dimensional photonic crystals, for example, three-dimensional etching method, wafer fusion laminating method, automatic cloning method or the like method is known in this respect.
Three-dimensional etching method means a method wherein a substrate is etched at various angles to produce three-dimensional photonic crystals involving three-dimensional structures. Furthermore, wafer fusion laminating method is the one wherein a plurality of semi-conductors formed into striped shapes are accurately positioned to laminate with each other by the use of a laser beam diffraction pattern, whereby three-dimensional photonic crystals involving three-dimensional structures are produced. Moreover, automatic cloning method is the one wherein an irregular surface has been previously formed on a substrate, and crystals are grown on the irregular surface retaining the surface morphology, whereby three-dimensional photonic crystals having three-dimensional structures are prepared.
However, any of the above-described conventional methods is not sufficient for producing three-dimensional photonic crystals applicable to optical devices, so that a proposition for a practically effective and novel method has been strongly demanded.